Carbon-doped single-crystalline SiGe/Si thermistor with high temperature coefficient of resistance and low noise level

Abstract

SiGe (C)/Si(C) multiquantum wells have been studied as a thermistor material for future bolometers. A thermistor material for uncooled Si-based thermal detectors with thermal coefficient of resistance of 4.5%/K for 100×100 μm2 pixel sizes and low noise constant (K1/f) value of 4.4×10−15 is presented. The outstanding performance of the devices is due to Ni-silicide contacts, smooth interfaces, and high quality multiquantum wells containing high Ge content.

High performance infra-red detectors based on Si/SiGe multilayers quantum structure

“…Although similar SiGe growth recipe was used for Si 0.72 Ge 0.28 /Si and Si 0.72 Ge 0.28 /Si 0.99 C 0.01 , the device containing C in the barrier benefits from wells with slightly higher Ge content (>28%) due to lower Si diffusion into the SiGe wells. Thus, growing Ge-delta layers at low temperature embedded in Si 1−y C y will be an ideal solution to create MQWs with very high TCRs and SNRs [17]. SIMS results indicated that the carbon amount at the interfaces (Si 0.99 C 0.01 /SiGe) is higher (as high as 2%) than compared to the barrier layer (Si 0.99 C 0.01 ).…”

Micromechanical Process Integration and Material Optimization for High Performance Silicon-Germanium Bolometers

“…Somewhat surprisingly it was realized that alternating layers of Si and SiGe layers showed a large TCR of about 3% and that the TCR value in fact was exponentially related to the band gap offset in this type of heterostructure. Empirical studies over a relatively wide range of Ge content x in the the Si 1-x Ge x alloy confirm this [24][25][26]. In analogy with so-called quantum-well infrared photodetectors, employing direct conversion of photon energy into free carriers, the term quantum well thermistors was used.…”

“…For normal CVD growth conditions the maximum Ge concentration has been limited to about 30%, except for a few cases where carbon has been added to stabilize the lattice [24]. Nevertheless, the TCR values for all these samples show a saturating trend, where it is difficult to reach a repeatable TCR in excess of 3%/K.…”

Group IV Materials for Low Cost and High Performance Bolometers

“…A vital issue in many cases for bolometers containing SiGe/Si MQW system is the control of the residual strain in the suspended membrane. Radamson et al (H. H. Radamson, Kolahdouz, Shayestehaminzadeh, Afshar Farniya, & S. Wissmar, 2010) reports the integration of C in the Si/SiGe stack (SiGe(C) / Si(C) MQWs) to create alternating tensile/compressive strain systems. The SiGe(C) layers were created through the intermixing of Si into the embedded Ge thin layers (grown by introducing GeH 4 without SiH 4 ).…”